Apparatus for signaling between two points on a railroad train



P. H. GEIGER Sept. 4, 1934.

APPARATUS FOR SIGNALING BETWEEN TWO POINTS ON A RAILROAD TRAIN INVENTOR: P. H. G i

Filed Dec. 17, 1929 s m A 1 mm wL m fi II. III- Patented Sept. 4, 1934 PATENT FFIC APPARATUS FOR SIGNALING BETWEEN TWO POINTS ON A RAILRQAD TRAIN Paul H. Geiger, Ann Arbor, Mich, assignor to The Union Switch &

Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application December 17, 1929, Serial No. 414,672

7 Claims.

My invention relates to trackway apparatus for use in connection with an electrical system of signaling through the track rails between two points on a railroad train, such, for example, as between the locomotive and the caboose of a freight train.

One form of system with which my invention may be used, is disclosedand. claimed in an ap plication for Letters Patent of the United States,

. filed by L. O. Grondahl on April 11, 1928,-Serial No. 269,148, for Apparatus for signaling between two points on a railroad train. In connection with the system disclosed in the said application, I have found that it is advantageous to connect the track rails with ground at a point behind and close to the rear of the train, or at a point ahead of and close to the train, or at both. One feature of my present invention is the provision of 'means for grounding the track rails in this manner. 1

I will describe two forms of trackway apparatus embodying my invention, and will then point out the novel features thereof in claims.

'In the accompanying drawing, Fig. 1 is .a 25 diagrammatic view showing one form of apparatus embodying my invention. Fig. 2 isa diagrammatic view showing a modification of one portion of the apparatus shown in Fig. 1,,and also embodying my invention.

Referring first to Fig. 1, the reference characters 1 and 1 designate the track rails of a railway track along which trafiic normally moves in the direction indicated by the arrow. These rails are divided by insulated joints 2 to form a plurality of successive track sections of which only three sections AB, B and CD, are shown in the drawing. Each of these sections is provided with the usual railway signaling track circuit comprising a track battery 4 connected across the rails at the exit end of the section, and a track relay connected across the rails at the entrance end of the section. Each of the track relays is designated by the reference character T with an exponent corresponding to the location. These track relays may be used for the control of wayside signals or other trafiic' Located adjacent the entrance end of each track section are two auxiliary condensers 5, which are connected in series across the two rails 1 and 1 The junction of each two condensers 5 is connected with the ground G through a front contact 6 of the adjacent track relay T. These condensers 5 should be of such capacitance that they ofier a relatively small impedance to alternating current of the frequency used for signaling on the train. The train signaling current willusually be of considerably higher frequency than that of the usual alternating current track circuits, and so when alternating current isused for the track circuits, the capacitance of the condensers 5 may be such as to ofier a very small impedance to the train signaling current and still not be great enough to seriously aifect the-operation of the track relays.

t will be notedthat the condensers 5 are connected in series for the track circuit current, and in parallel for the train signaling current. The operation of the apparatus shown in Fig. 1, is as follows: As shown in this view, a train F is located at point C, so that this trainoccupics the entrance end of section CD, and the exit end of section B'C'. Track relay T is therefore open; so that the train signaling current is not grounded by the condensers 5 at lo cation C. If the transmitter on the locomotive of this train is operating, the current'induced in the track rails will flow through the rails and the condensers 3 at location C, thence through the track rails of section B-C, the condensers 3 at location B, the track rails of section A-B, the condensers 5 at location A, and contact 6 of track relay '1" to ground G. The current will then flow through the ground to point G at location D, thence through contact 6 oftrack relay T condensers 5 at location D, condensers 3 at location D, and the rails of section CD to the transmitter on the locomotive of train F.- It will be observed that this path has a lower resistance than if the condensers 5 were omitted, because in the absence of condensers 5 the connections of ground would have to be made through the rail-to-ground resistance.

Referring now to Fig. 2, the apparatus shown in this view is the same as that shown in Fig. 1, except that each track circuitis provided with an auxiliary relay X interposed between the.

track battery 4 and one of the track rails vl This relay is adjusted to be open'when the track section is unoccupied, and to be closed when a train is near the exit end of the section. This adjustment does not need to be critical, because l as;

satisfactory operation will be obtained if the relay closes when any part of the section is occupied by a train, or if it closes only when the train is at the exit end of the section. Each auxiliary relay X is provided with a back contact 7 which is connected in multiplewith the front contact 6 of the adjacent track relayT.

The operation of the apparatus shown in Fig. 2, is as follows: I will assume, as before, that a train F is located at point C, so that this train occupies the entrance end of section CD and the exit end of section B c. Track relay T is open, and auxiliary relay X is closed, so that the condensers 5 at location C are not connected with ground. Auxiliary relay X is open, so that condensers 5 at location Dare connected with ground whether or not track relay T is closed, that is, whether or not the section to'the right of point D is occupied. At location B, track relay T is, of course, open, due to the presence of a train in section BC, but auxiliary relay X is also open, so that condensers 5 at this location are connected with ground through the back contact '7 of this relay. It follows that if the transmitter on the locomotive of train F is operating, the current induced in the track ground at a shorter apparatus rails by this transmitter will pass to points B and D, thereby providing path than the path provided by the shown in Fig. 1.

One advantage due to my invention, is that the amount of power required for signaling on the train is less than if the condensers 5 are not provided. Another advantage is that the transmission of signals between two points on the train will not be affected by changes in the track ballast resistance as much as would be the case if the condensers 5 were not provided. Still another advantage, is that the possibility of the signals'from one train reaching another train, is greatly reduced, because the train sig naling current flows through a smaller number of track sections than if the condensers 5 werenot provided.

Although I have herein shown and described only two forms of apparatus embodying my invention, it is understoodthat various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention. 7

Having thus described my invention, what I claim is: r

1. Trackway apparatusfor use in connection with an electrical system of signaling through the track rails between two points on a train, comprising, in combination with the usual insulated track sections each provided with the usual track circuit, two condensers connected in series across the rails of each track section, and a connection from the junction of each of said two condensers to ground including a front contact of the associated track relay.

2. Trackway apparatus for use in connection with an electrical system of signaling through the track rails between two points on a train, comprising, in combination with the-usual insulated track sections each provided with the usual track circuit, two condensers connected in series across the rails of each track section, a connection from, the junction of each of said two condensers to ground including a front contact of the associated track relay, an auxiliary relay for each section interposed between the source of track circuit current and one of the rails and arranged to be open when the section is unoccupied and closed when a train is near the exit end of the section, and an auxiliary connection from the junction of each said two condensers toground including aback contact of the auxiliary relay for the section next in the rear.

3. Trackway apparatus for use in connection with an electrical system of signaling through the track rails between two points on a train, comprising, in combination with the usual insulated track sections each provided with the usual track circuit, two condensers connected in series across the rails of each track section, and means for connecting the junction of each said two condensers directly in front of and in the rear of a train with ground.

4. Trackway apparatus for use in connection With an electrical system of signaling through the track rails between two points on a train, comprising, in combination .with the usual in sulated track sections each provided with the usual track circuit, a condenser connected across each insulated joint, a pair of auxiliary condensers connected in series across the rails of each track section, and a connection from the junction of each pair of auxiliary condensers to ground including a front contact of-the associated track relay.

5. Trackway apparatus for use in connection with an electrical system of signaling through the track rails betweentwo pointson a train, comprising, in combination with the usual in- M sulated track sections each provided with the 119 usual track circuit, a condenser connected across each insulated joint, a pair of' auxiliary condensers connected in series across the rails of each track section, a connection from the junc tion of each pair of auxiliary condensersto ground including a front contact of the associated track relay, an. auxiliary relay" for each section interposed between the source of track circuit current and one of the rails and arranged to be open when the section'is unoccupied and closed when a train is near the exit end of the section, and an auxiliary connection from the junction ofeach pair of auxiliary condensers to ground including a back contact of the auxiliary relay for'the section next in 125 the rear.

6. Trackway apparatusfor use in connection with an electrical systemof signaling through the track rails between two points on a train, comprising, in combination with the usual in-- 136 sulated track sections each provided with the usual track circuit, a condenser connected across each insulated joint, a pair of auxiliary condensers connected in series across the rails of eachtrack section, and -means for connecting 135 the junction ofeach pair of auxiliary condensers next in front of and next behind a train with ground. I

'7. Trackway apparatus for use in connection with an electrical system, of signaling through 146 the track rails between two points on a train, comprising, in combinationwith the usual insulated track sections each provided with the usual track circuit, two condensers connected in series across the rails of each track section, and 145 means for connecting the junction of each said two condensers with ground when the associated track relay is closedbut not when it is open.

PAUL H. GEIGER. 

